The purpose of this study is to describe the intiating and control factors of hepatic gluconeogenesis in the immediate newborn period. Gluconeogenesis does not occur in utero, but develops shortly after birth. The capacity to generate glucose and establish metabolic homeostasis is critical for subsequent intact cerebral function. The newborn piglet will be used in this study for two reasons; one, he is unable to initiate gluconeogenesis if fasted from birth, and second, he is relatively deficient in adipose tissue. It is our hypothesis that the oxidation of fatty acids by the liver is essential for the development of gluconeogenesis. To test the hypothesis, we have designed two experiments. The first is to establish a developmental curve for hepatic acyl carnitine transferase activity and to determine the role fatty acids play in the induction of this enzyme activity. We will also investigate whether the piglet can synthesize carnitine or must obtain it from his diet (sow's milk). After the developmental curve for acyl carnitine transferase activity has been determined, experiments will be performed which involve the simultaneous infusion of fatty acids complexed to albumen and radioactive precursors in one member of a matched pair. The precursors tested will be lactate 3-C14, pyruvate 3-C14, and alanine-U-C14. By using matched pairs with only one receiving intravenous fatty acids, we will be able to determine whether the hypothesis is correct. A third group of experiments relating glucose homeostasis and cold stress are proposed. In these studies, glucose pool size and turnover rate will be determined by isotope dilution methods in mildly cold (23 degrees C) and neutral thermal animals. Gluconeogenic rates will be determined either in a cold or neutral thermal environment. These experiments will provide data necessary to examine the question of whether mild cold stress in the neonate increases glucose consumption beyond maximal generation rate and results in hypoglycemia. If this it true, important alterations in the management of human infants might be considered. Last, we feel this study will establish the piglet as an excellent model for neonatal metabolic studies in the future.